Manufacture of molded products of silicon carbide is generally based on subjecting pressure and heat to silicon carbide powder mixed with a sintering assistant in a graphite press tool. With zero-pressure sintering method, the thus pressed material is burned in a vacuum or non-oxidizing atmosphere. According to reaction sintering method, the formation of silicon carbide from its materials and the sintering of silicon carbide are carried out successively. There are also known self-sintering method, and silicon-injection sintering method and so on as conventional methods. Each of these methods has, however, the disadvantage that only products having a relatively simple shape, such as planar or columnar, can be obtained. In order to obtain molded products having a more complicated shape, there have been proposed improved methods, such as powder vehicle or pseudoisostatic hot press method, multi-punch hot press method and hot isostatic press method, each of which consists essentially of compacting the molded material filled in a powder vehicle. These methods, however, provide products still limited in shape and dimensions, and require complicated facilities of high performance and a high manufacturing cost.
As one of the methods of molding the material to be sintered, sheet dipping method, which is a method for molding mainly thin plates, is known. This method comprises dipping paper with a coagulant adsorbed on the surface thereof in a slurry in which ceramic powder is peptized, and fixing the powder on the paper surface by ion exchange. Japanese Patent Application No. 46-7604 discloses a method of making paper from a mixed slurry composed of cellulose pulp and a ceramic powder which is used as a filler. These methods, however, have problems of low ceramic powder content, limited range of moldability and low yield owing to cracking or deformation on burning. Morevoer, when silicon carbide is used as a material for the molded product, a high burning temperature not lower than 1,700.degree. C. is generally required since silicon carbide is difficult to sinter.